Polymer webs have been made by electrospinning, rotary spinning, centrifugal spinning, melt spinning, extrusion melt spinning, air laid processing, or wet laid processing. The filtration efficiency of such filters is characteristic of the filtration media and is related to the fraction of the particulate removed from the mobile fluid stream.
Fine fiber technologies that contemplate polymeric materials mixed or blended with a variety of other substances are known. Certain of the disclosed fibers comprise an axial core or a polymeric material. Surrounding the axial core can be found a layer of a coating material such as a phenolic oligomer or a fluoropolymer component. While many of these fine fiber materials have adequate performance for a number of filtration end uses, in applications with extremes of temperature ranges, where mechanical stability is required, improvements in fiber properties is still needed.